Here is the mortise for the joint.
This is the pair done and fitted to the opening. The folks at the fort were pleased to see this pair go in as it provides light for the gift shop.
This is the pair next to the existing windows.
The last sash that I had to build was a casement sash that had the same proportions as the pair I just discussed. The opening for this casement is in the office but originally it was the woodshed and privy. The opening was covered by a shutter which has long since disappeared. The fort has some old photos showing the shutter opened. I thought that a casement would be appropriate since it opens in the same direction as the old shutter and the building has casement windows in it already.
Here are some photos of the completed casement.
The casement is the one on the right.
The rotten sill. Once I removed the rot about 2/3 of the sill remained intact. My general rule is at 50% rot then replacement of the element should be considered. In some cases I would argue that even if just the smallest amount original material is sound it should be saved. It depends upon the historical significance of the structure.
The sill repaired with a salvaged beam from Aurora Mills and some epoxy.